The prediction of coaxial spline tooth wear requires knowledge of the tooth loading and relative movement characteristics, as well as the mechanisms for fretting wear, fretting corrosion, fretting fatigue, and reciprocating wear. This paper presents the proposed mechanisms and theories of many researchers. Also presented is a model developed for the purpose of this analysis that can be used to determine the number of teeth in contact, contact stresses, sliding amplitudes, and pressure velocity products for a given coaxial spline configuration. These results can then be analyzed in terms of relevant wear theories to predict life and performance characteristics. While the model was initially developed to predict and improve the performance of coaxial splines in applications involving clutches, it can also be used to predict the interactions of splined couplings.